Background of the Invention
1. Field of the Invention
[0001] This invention relates to a catalyst support with a unique bidisperse micropore size
distribution and to the resulting hydroprocessing catalyst which is made from the
support and to a process to hydrotreat heavy petroleum feeds.
Description of the Previously Published Art
[0002] Shiroto et al in U. S. Patent 4,444,655 discuss extensively eight different types
of processes for hydrotreating using various kinds of catalysts and point out that
none of the processes is satisfactory. Their solution is to use a catalyst having
1-30% by of catalytic metals (1) where the average pore diameter (APD) is from about
180 to 500 Angstrom units, (2) where the minimum total pore volume is calculated by
a formula which is dependent on the APD and which has at least 0.35 cc/
g of volume in pores from 180 to about 500 Angstrom units and (3) where the total surface
area is at least 104 m
2/g.
[0003] Of interest to the present invention is Shiroto et al's description of processes
for hydrodesulfurization and demetallization characterized by using a catalyst having
a double peak in its pore volume. This is their prior art process (5) which they say
"is based on the fact that in the hydrotreatment of heavy hydrocarbon oils, desulfurization
is not very largely influenced by intrapore diffusion, while demetallization is largely
affected by it. According to this process, there is used a catalyst provided with
both small pores having a diameter not greater than about 100 Angstrom units, and
macropores having a diameter of at least about 500 Angstrom units, or even at least
about 1,000 Angstrom units. Although this catalyst does certainly relax the limitations
relating to the diffusion of metal-containing high molecular compounds into the pores,
it shows a sharp reduction in activity due to metal accumulation in the pores having
a diameter not greater than about 100 Angstrom units, and the mouths of these pores
are likely to be blocked, as is the case with the catalyst used for the group (1)
[which is their prior art catalyst with small pores]. Thus, the catalyst for the group
(5) fails to maintain a high activity for a long time for the feedstock oil having
a high metal content, and eventually, only the larger pores act mainly for demetallization.
Therefore, it is not considered to have an improved efficiency over the catalysts
for groups (1) and (3) [which is their prior art catalyst with macro pores] which
are used individually."
[0004] Mulaskey in U. S. Patent 4,102,822 discloses a catalyst composition in the form of
a pack of particles with different size particles without reference to the pore size
distribution of these particles. There are channels forming interconnected macropores
which contribute from 3 to 45 of the pore volume. A further and special advantage
of the catalyst is that a mixture of two or more different kinds of particles having
different catalytic activities may be used in the preparation of the catalyst pack
or cluster therein, thereby yielding a catalyst having bi- or polymodal activity.
Objects of the Invention
[0005] It is an object of this invention is to prepare a catalyst support containing a bidisperse
distribution. A catalyst having a bidisperse micropore structure has a bimodal pore
size distribution in the micropore region.
[0006] It is a further object of this invention to prepare a desulfurization and demetallization
catalyst containing a bidisperse micropore size distribution.
[0007] It is a further object of this invention to hydroprocess heavy feeds by utilizing
an improved catalyst having a bidisperse micropore size distribution.
[0008] It is a further object of this invention to prepare a catalyst support containing
a bidisperse micropore size distribution and a controlled amount of macroporosity.
[0009] It is a further object of this invention to prepare a catalyst support containing
a bidisperse micropore size distribution wherein different materials are used together
to achieve the desired pore diameters.
[0010] These and further objects will become apparent as the description of the invention
proceeds.
Summary of the Invention
[0011] Catalyst supports and preferred desulfurization and demetallization catalysts are
made with a bidisperse micropore size distribution in the micropore region. The pore
volumes of the two micropore modes are chosen such that feed molecules can diffuse
into the pellet via each of the microporous pathways.
[0012] The size of the smaller micropores serves to screen out the larger metal containing
molecules from entering the pores according to a "screen door" effect described by
Hamner in U. S. 4,051,021. This screen door effect is a phenomenom that permits entry
of relatively small molecules such as sulfur into the pores while simultaneously inhibiting
the entry of relatively large molecules. In Hamner's patent, the catalyst had only
small pores and the larger molecules passed through the reactor virtually untreated.
It is the object of the present invention to optimally provide both small and larger
micropores within a single catalyst pellet.
[0013] The higher surface activity of the small micropore materials will enhance the hydrodesulfurization
activity of the catalyst. The smaller micropore region, which screens out the larger
metal bearing molecules while allowing entry to the smaller sulfur molecules, typically
has an average diameter of less than 100 Angstrom units.
[0014] The larger micropores are chosen such that the pore size is equal to or larger than
100 Angstrom units and much larger than the average diameter of the metal bearing
molecules. As will be discussed below, the average metal bearing molecules have sizes
of 20 Angstrom units or higher as determined, for example, by Gel Permeation Chromatography
or Size Exclusion Chromatography with an Inductively Coupled Plasma. Thus larger micropores
will result in increased catalyst demetallation activity and life. The larger micropore
region has larger micropores where the average diameter is between about 100 and 600
Angstrom units and more preferably between 100 and 250 Angstrom units.
[0015] These catalyst supports can be made in the form of formates such as extrudates. As
a result there may be larger pores between the grains of the refractory oxide which
will serve as macropores.
[0016] By adding various known desulfurization metals and demetalization metals in each
of the two micropore modes very effective catalysts can be formed for use in hydroprocessing
heavy feeds. In one embodiment for making the catalyst support two different types
of powders are mixed together. One provides the small micropores and the other provides
the larger micropores. In another embodiment either powder can be preloaded with desulfurization
and/or demetallation metals.
[0017] Although the exact theory of how the catalyst works is not known, perhaps the following
analysis will aid in understanding the invention. The large-micropore, low-metals
impregnated fraction of the catalyst are thought to allow the metals in the petroleum
which are to be removed to access the catalyst internals where they react within the
catalyst pores and deposit as metal sulfides. The small-pore alumina fraction impregnated
with desulfurization metals such as Co and Mo are considered to provide the necessary
desulfurization activity.
Brief Description of the Drawings
[0018]
Fig. 1 is a representation of the two types of materials which can make up the catalyst
support in a preferred embodiment.
Fig. 2 is a graph illustrating the initial selectivity of hydrotreating catalysts.
Fig. 3 is a comparison of bidisperse micropore size catalysts and unimodal unidisperse
catalysts of varying micropore diameter.
Fig. 4 is a graph illustrating the pore volume distribution versus the pore diameter
for the bidisperse micropore size.
Fig. 5 is a graph illustrating the pore volume distribution versus the pore diameter
for the bidisperse micropore size supports containing macropores.
Fig. 6 is a graph illustrating the pore volume distribution versus the pore diameter
for the bidisperse micropore size catalysts containing macropores.
Description of the Preferred Embodiment
[0019] The catalyst support and resulting catalyst is made of two types of micropore materials.
As seen in Fig. 1, the small pore micropore material can be designated Material 1
and it preferably has an average pore diameter below about 100 Angstrom units. The
larger micropore material is designated Material 2 in Fig. 1 and it is chosen to preferably
have a pore diameter much larger than the size of the metal bearing molecules in the
heavy feed being treated for desulfurization and demetallization. Since the molecular
size distribution for the metal bearing species may range from 20 Angstrom units to
as large as 100 Angstrom units, the size of the larger micropore is chosen so that
most of the molecules can easily diffuse through. In general the large micropore region
should have larger micropores where the average pore diameter is at least five times
the average diameter of the metal bearing molecules in a heavy feed to be processed.
Preferred average pore diameters are between about 100 and 600 Angstrom units and
more preferably between 100 and 250 Angstrom units. The amount of the small micropore
material and the large micropore material can each range from 5% to 95% by weight
of the total with the more preferred ranges being 30%-70%.
[0020] Surface area is measured using the BET technique that is standardly practiced in
the art. The cumulative pore volume distribution is obtained using Hg porosimetry.
In this method, the pressure of Hg is increased and the volume intruded into the sample
is measured. The instrument used was a Micromeretics Autopore 9200. The pore volume
distribution is obtained by relating the intrusion pressure to diameter (using a contact
angle of 140°) and by differentiating the cumulative pore volume distribution. An
example of such a distribution is shown in Figure 4 and consists of two distinctly
separated peaks in the micropore region. A point in between the two peaks is identified
and the pore volume in each of the micropore modes is obtained. Hg porosimetry is
also used to calculate the fractional contribution of each of the micropore modes
to the total surface area. For a fraction alphas of surface area from smaller micropores,
the diameters are calculated as

and

[0021] The size of the metals bearing molecules will vary depending on the quality and type
of the feedstock treated. For example, using analytical and preparative Gel Permeation
Chromatograph at ambient conditions, the average size of the vanadium bearing molecules
may be as large as 65 Angstrom units for an Arab Light vacuum resid and 40 Angstrom
units for a Wilmington crude (Hall and Herron, Adv. Chem. Ser., 195, 1981, page 149).
Processing conditions such as temperature, pressure, and gas composition (as, for
example, hydrogen partial pressure) may also effect the size of the metal and sulfur
bearing species. The larger asphaltenic molecules are believed to deflocculate at
reaction conditions thereby reducing their size. This is evident from the fact that
at higher temperatures a larger fraction of the asphaltenes are able to enter the
pores of a given catalyst (Richardson and Alley, Prepr. Div. of Petr. Chem., American
Chemical Society, Philadelphia, 1975).
[0022] Most of the metals are contained in the maltene and asphaltene fractions of the feedstock.
The size of the metal bearing species at reaction conditions varies from 20 to 50
Angstrom units. Larger micropore diameters in the range of 100-600 Angstrom units
would allow metal molecules to easily access the internals of the catalyst.
[0023] Most of the sulfur bearing species in heavy oils are either thiophene, benzothiophene
or dibenzothiophene based and have a molecular size of between 6 to 10 Angstrom units.
A small fraction of the sulfur may also be present in the asphaltene fractior and
have a larger molecule size. Smaller micropore diameters in the range 30-100 Angstrom
units would be suitable for the treatment of most of the sulfur species.
[0024] The two sizes of micropores can be formulated by various means. For example, one
can use different forms of alumina. One form would be made of grains of small micropores
while the other form is made of grains of larger micropores. By mixing these two forms
together one obtains the desired mixture. As another example, one could take grains
of one pore size of alumina and calcine a portion to change its pore size. A third
possibility is to use two completely different materials having different pore sizes
such as alumina and silica. These grains could then be mulled together and extruded
in a manner standardly practiced in the art. Calcination treatment after extrusion
could be used to additionally modify the pore structure of the extrudate.
[0025] After mixing together the two different size micropore materials they can be extruded
to form formates. During the process of extrusion there may be channels between the
various grains which form macropores having diameters greater than 600 Angstrom units.
Such a resulting catalyst support can be characterized trimodal since it has a bidisperse
micropore size characterization with the two different types of micropore regions
and it then has this third region of much larger micropores.
[0026] To form the catalyst various metals can be added to the catalyst support. Among the
conventionally known desulfurization metals are metals of Group VIB such as Cr, Mo
and W and Group VIII which include Fe, Co, and Ni in addition to six other members
which are Ru, Rh, Pd, Os, Ir and Pt with preferred metals being Mo, W, Ni and Co,
with especially preferred metals being Co and Mo. After the Co and Mo are added to
the catalyst and calcined it forms CoO and MoO
3 and this MoO3 can be present in an amount of 0.1-30% by weight with CoO present in
the 0.1-5% by weight range. The demetallization metals include members of Group VIB
which are Cr, Mo and W; members of Group VIII as listed above; members of Group VB
which are V, Nb and Ta; and members of Group VIIB which are Mn, Tc and Re. Especially
preferred metals are Mo as well as other low activity and especially hydrogenation
metals such as Fe, Mn, Ni, Co, and W. Again these metal oxides can be present in a
weight range of 0.1-30% by weight.
[0027] In general it is preferred to have the Mo oxide present in the small micropores in
an amount of 8-30% by weight and to have the metal oxide present in the larger micropores
in an amount of 0.1-8% by weight. One way to obtain this different level of metal
oxide loadings is to impregnate the small micropore grains with desulfurization metals
such as Co and Mo and to then separately impregnate the large micropores with either
a different material which is a demetallization metal or to a lesser extent.
[0028] Another preparation method that may be used is the equilibrium adsorption of metals
onto the alumina surface with an excess of impregnation solution. In this case, the
Mo loading in each of the grains will be proportional to the local surface area.
[0029] Catalysts can also be prepared by the incipient wetness method of impregnation which
is standardly practiced in the art.
[0030] Catalysts can also be prepared by first forming particles of a refractory oxide powder
having a small micropore region having an average pore diameter of less than 100 Angstrom
units and a large micropore region having an average pore diameter which is much larger
than the average diameter of the metal bearing molecules in a heavy feed to be processed.
Then the particles are calcined to form a catalyst support which is impregnated with
one or more catalytic metal components selected from the group consisting of a metal
belonging to Group VB, VIB, VIIB and VIII of the Periodic Table. These catalytic metal
components are present in an amount of between about 0.1% and about 30% in terms of
metal oxide based on the total weight of the catalyst.
[0031] Another way to make the catalysts is to first impregnate particles of a refractory
oxide powder having a small micropore region with an average pore diameter of less
than 100 Angstrom units with one or more desulfurization catalytic metal components
belonging to Groups VIB and VIII of the Periodic Table. These impregnated particles
are then mixed with a refractory oxide powder having a large micropore region with
an average diameter which is much larger than the average diameter of the metal bearing
molecules in a heavy feed to be processed. The mixture is formed into catalyst particles
and the particles are calcined to form a hydrotreating catalyst. In a further modification
of this embodiment, after the catalyst particles are formed and before calcination,
the catalyst particles can be further impregnated with one or more demetallization
catalytic metal components belonging to Groups VB, VIB, VIIB and VIII of the Periodic
Table. Then after the calcination the resulting catalyst will have desulfurization
metals in the small pores in the proper amount and the demetallization metals in the
larger pores.
[0032] Catalyst of this invention prepared having less than 5% of pores of diameter greater
than 600 Angstrom units are preferred in the treatment of lighter feeds because of
increased surface area. Macropores would reduce the active surface area per volume
of reactor but may be preferred in cases where high metal levels in the feed may cause
external plugging of the catalyst pores.
[0033] In addition to extruding the material in conventional cylindrical shapes, it is also
possible to extrude in any type of geometrical shape including in the shape of an
extrudate support structure having a cylindrical hollow annular configuration with
internal reinforcing vanes as disclosed in USP 4,510,263.
[0034] The catalysts can be used in a process for hydrotreating a heavy hydrocarbon oil
containing asphaltenes. Such a process involves preferably reacting the heavy hydrocarbon
oil in the presence of the catalyst with hydrogen at a temperature of between 300°
and 500°C, with a hydrogen pressure of between 50 and 250 atmospheres and with a liquid
space velocity of between 0.1 and 10 hour .
[0035] Although the exact mechanism as to how the present catalyst exhibits such superior
results is not known, the following mathematical rationale may provide some theoretical
and conceptual explanation. Consider a bidispersed micropore size extrudate made up
of grains having two different pore structures and activites but the same total porosity
as shown in Figure 1. The effective diffusion coefficient in each grain is given by

where D
i is the effective diffusion coefficient in the absence of configurational diffusion,
d is the pore diameter, and i = micrograin (i=l), macrograin (i=2) or macropore (i=3).
The effective diffusion coefficient in the catalyst pellet (2)

where f is the porosity. The Thiele modulus (defined standardly in chemical reaction
engineering) is given as

where R is the equivalent radius of a spherical pellet and η
i is the effectiveness factor,

where 1
. is the diameter of the grain and k
i is the volumetric rate constant. The conversion at the reactor outlet for a first
order reaction rate

where ε
r is the reactor void fraction and LHSV is the liquid hourly space velocity.
[0036] Let us assume that the rate constant k
. is proportional to the surface area of the grain. This would typically be the case
if the catalysts were prepared using an equilibrium adsorption process with excess
impregnation solution. Also, assume that the sulfur containing molecules are 7 Angstrom
units in size, that the metal bearing species are 40 Angstrom units in size and that
the intrinsic rate constant for both metals and sulfur removal is the same. We can
now construct a selectivity diagram as shown in Figure 2. Curve I in Figure (2) illustrates
the initial selectivity performance of a unimodal catalyst having 70 Angstrom units
micropores. Curve II in Figure 2 represents the initial activity of a 200 Angstrom
units unimodal catalyst. Points A and B show the initial activity of the small and
large pore catalysts at the same
LHSV. Curve III (Figure 2) shows the initial selectivity performance of the catalysts
of this invention. The catalysts are prepared by mixing various volume fractions of
grains having 70 Angstrom units and 200 Angstrom units pores. Catalyst desulfurization
activity decreases as one proceeds from Point A to Point B along Curve III in Figure
2. However, the demetallation activity is maximum at Point C. A catalyst at point
C would contain from 30-40 vol % of the smaller pore material.
[0037] Unimodal catalysts having larger sized micropores can also be prepared for comparison.
Figure 3 compares the initial performance of the catalyst of this invention with that
of a unimodal micropore catalyst of varied micropore diameter. The catalyst of this
invention represented by the solid line has a higher initial metals removal at a fixed
desulfurization level compared with the various unimodal micropore catalysts represented
by the dashed line.
[0038] We also believe that the catalyst of the invention will have a longer life compared
with a catalyst having only the smaller micropores. Since a substantial fraction of
pores on the external surface on the catalyst are larger micropores, the time for
catalyst deactivation via pore mouth plugging will be comparable to that of a catalyst
having only larger micropores.
[0039] To illustrate the superior selectivity characteristics of the bidisperse micropore
size catalyst, we have compared the performance of such a catalyst with that of unidisperse
catalysts having smaller and larger micropore diameters in Examples 5, 6 and 7. As
is seen from Tables (4), (5) and (6), the catalyst of the present invention shows
superior performance compared with the other unidisperse catalysts.
[0040] After having described the superior catalysts according to the present invention
and having presented the mathematical model analysis above which supports the unique
results that our catalyst can obtain, it is interesting to return to the Shiroto patent
on hydrotreating. The Shiroto et al patent divides hydrotreating developments for
the removal of sulfur, metals, nitrogen, and asphaltenes fall into eight categories.
Neither it, nor any other patents of which we are aware, discuss catalysts with bidisperse
micropore size distributions as in the case of the present invention. Shiroto et al's
category (3) relates to catalysts with pores greater than 200 Angstrom units which
are also the type of pores used in his catalyst. Such catalysts show superior metals
and asphaltene removal activity and durability. However, the desulfurization activity
of such catalysts is lower because of the lower surface area of the catalyst.
[0041] Categories (4) and (5) in the Shiroto et al patent discuss overall bimodal pore size
distribution in which the pores greater than 200 Angstrom units serve as access channels
into the catalyst. However, the incorporation of such large pores inevitably leads
to a decrease in the available alumina surface area per reactor volume and to lower
hydrodesulfurization activity. In the present invention, the pore diameter of the
larger micropores is reduced so the larger micropores contribute significantly to
the surface area. This can be accomplished by sizing such pores in the range of 100-600
Angstrom units and preferably in the 100-250 Angstrom units range. The smaller micropores
provide the necessary surface area to accomplish desulfurization. Similarly we prefer
to make the macropores formed by the channels between the grains be as small as possible
without restricting diffusion into the pellets so as to increase surface area.
[0042] Having described the basic aspects of our invention, the following examples are given
to illustrate specific embodiments thereof.
Example 1
[0043] This example illustrates making a bidisperse micropore size catalyst support according
to this invention which is substantially free of macropores (i.e. with a diameter
greater than 600 Angstrom units).
[0044] A slurry of 450 grams of Davison SRA alumina in 950 ml of water was heated in a 2
liter autoclave at 175°C for 4 hours. The alumina was dried at 110°C. The hydrothermal
treatment increases the pore diameter of the alumina. Mixtures of the hydrothermally
treated SRA and Catapal were used to prepare extrudates with bidisperse microporosity.
In one procedure identified as Run A, 150 g of hydrothermally treated SRA were mixed
with 150 g of Catapal and mulled with 170 ml of a 0.35% polyvinyl alcohol solution.
In the second procedure identified as Run B, 193 g of hydrothermally treated SRA were
mixed with 400 g of Catapal and mulled with 320 ml of a 0.6% polyvinyl alcohol solution.
The pore structure of the 1/20 inch extrudates after calcination for 2 hours at 1400°F
is shown in Figure 4. The macropore volume of these samples has been reduced to less
than 0.07 cm
3/g. The pore structures are set forth in Table 1.
Example 2
[0045] This example demonstrates the flexibility in controlling the relative pore volumes
of the two different size micropores to make catalyst supports.
[0046] Three bidisperse micropore size extrudates were prepared by combining varying amounts
of calcined SRA (2 hours at 1750°F) with uncalcined Catapal which is an alumina made
by Conco Co. and which has micropores of around 30-80 Angstrom units. The extrudates
labelled A, B and C contained respectively 10, 20, and 50% alumina from the calcined
SRA. The extrudates were calcined for 2 hours at 1100°F and their pore size distributions
are shown in Figure 5. The pore structures are set forth in Table 1.
Example 3
[0047] This example illustrates that the bidisperse micropore size distribution support
may be obtained by extrusion of powders of different chemical compositions.
[0048] Two hundred grams of SRA alumina were mixed with 86 grams of a large pore silica
(Davison ACOD 243) in a Simpson Mix-Muller for 5 minutes. A solution of 16.3 ml of
HNO
3 in 240 ml of water was added to the powder and mulling continued until the mixture
turned to a soft paste. The paste was neutralized with 13.4 ml of concentrated NH
40H and extruded into 1/16 inch extrudates. The extrudates were calcined for 2 hours
at 1600°F. The pore size distribution is shown in Figure 6. There are two pore size
distributions in the micropore regions. One has a pore diameter of about 341 Angstrom
units and the other has a pore diameter of about 100 Angstrom units. The pore structure
is set forth in Table 1.

Example 4
[0049] A trimodal extrudate catalyst according to the present invention was made as follows.
[0050] SRA alumina powder which was prepared according to the method set forth in U. S.
Patent 4,154,812 was calcined at 1800°F for 2 hours. Catapal alumina powder obtained
from Conoco was separately impregnated with 14.7% MoO
3 and 3.3% CoO by the pore filling method with a solution of ammonium heptamolybdate
and cobalt nitrate. The impregnated powder was dried at 230°F. A 50:50 by weight mixture
(on an Al
2O
3 basis) of the calcined SRA powder and the impregnated Catapal was mulled together
and extruded as 1/16" cylindrical extrudates. These extrudates were further impregnated
with molybdenum and cobalt by spraying with a solution of ammonium heptamolybdate
and cobalt nitrate such that the resulting catalyst had 12.9% MoO
3 and 3.0% CoO on a total catalyst basis. This catalyst was oven dried and calcined
at 1100°F for 3 hours.
[0051] The physical properties are set forth in Table 2.
Comparison Example 1
[0052] A bimodal extrudate catalyst was made as follows.
[0053] A commercially available 1/16 inch extrudate catalyst contained 16.7% MoO
3 and 3.9% CoO on a total catalyst basis.
[0054] The physical properties are set forth in Table 2. It is bimodal in the sense that
it has micropores and much larger macropores. It does not have the micropore region
divided into two zones.
Comparison Example 2
[0055] A bimodal cylindrical extrudate of 1/16 inch diameter was prepared from SRA alumina.
This support was calcined for two hours at 1600°F and impregnated with a solution
of crude phosphomolybdic acid and cobalt nitrate to obtain a catalyst having 15% MoO
3, 3.3% CoO and 1% P on a total catalyst basis. The catalyst was oven dried and calcined
at 1000°F for two hours. The physical properties are set forth in Table 2. Again,
it is bimodal in the sense that it has micropores and much larger macropores, but
it does not have the micropore region divided into two zones.
Comparison Example 3
[0056] A commercially available unimodal catalyst having 14.4% MoO
3, 3.18% CoO, 9.9% SiO
2 and 0.11% P was obtained for comparison. This catalyst has a small micropore diameter
of 78A. The physical properties are set forth in Table 2. It does not have any larger
size pores to treat or carry in the large metal bearing molecules.
Comparison Example 4
[0057] A bimodal cylindrical extrudate of 1/16 inch diameter was prepared from SRA alumina.
The support was calcined for two hours at 1400°F and impregnated with a solution of
cobalt nitrate, ammonium heptamolybdate and citric acid to obtain a catalyst have
12.9% MoO
3, 2.9% CoO on a total catalyst basis. The catalyst was oven dried and calcined at
1000°F for two hours. The physical properties are set forth in Table 2. The catalyst
is bimodal in the sense that it has micropores and much larger macropores, but it
does not have the micropore region divided into two zones.

Example 5
[0058] The catalysts according to Example 4 and Comparison Examples 1-3 prepared above were
compared for their initial activity for sulfur and metals removal.
[0059] The catalysts were evaluated at a liquid hourly space velocity (LHSV) of 0.5 using
a Lloydminster feed (the properties of which are set forth in Table 3) at a temperature
of 750°F, a pressure of 1500 psi and a hydrogen circulation of 5000 scf/bbl. The stabilized
initial activity comparisons after 36 hours of testing for sulfur, nickel and vanadium
removal are set forth in Table 4.

[0060] The catalyst of Example 4 according to the present invention is seen to be clearly
superior for sulfur and metals removal. The two bimodal catalysts of Comp. Exs. 1
and 2 have similar micropore volumes as our catalyst of Example 4, but they do not
have the micropore region divided into two zones as is the present catalyst with its
bidisperse micropore size region having one mode with a diameter below 100 Angstrom
units and a second mode, above 100 Angstrom units, having a diameter of 140 Angstrom
units. These two comparison catalysts have similar activity, but in all instances
they are not as selective as our catalyst.
[0061] The unimodal catalyst of Comp. Ex. 3 does not have the larger pores needed for demetalization
and thus it is seen to have the lowest metals activity of all of the catalysts.
Example 6
[0062] This example illustrates the durability testing of the catalysts.
[0063] The catalysts of Example 4 and Comparison Examples 1, 2 and 3 were compared for sulfur
and metals removal for 40 days on stream. The conditions of the test were Lloydminster
vacuum resid, 750°F, 1500 psi, 1.0
LHS
V and a hydrogen circulation of 4000 scf/bbl. The relative activities of sulfur and
metals removal as a function of time on stream are shown in Table 5.

The catalyst of the present invention in Example 4 shows superior performance in demetallation
over all other catalysts tested and is only marginally less active to Comparison Example
1 in desulfurization after 30 days on stream.
Fxample 7
[0064] This example illustrates another durability testing of the catalysts.
[0065] The catalyst of Example 4 and Comparison Example 4 were compared for sulfur and metals
removal using a Boscan Feed, the properties of which are set forth in Table 3. The
reactor was operated in the upflow mode and the conditions of the test were 750°F,
2000 psi, 1.0 LHSV and a hydrogen circulation of 4000 scf/bbl. The relative activities
for sulfur and metals removal are shown in Table 6. The catalyst of the present invention
in Example 4 shows superior demetallation and desulfurization performance and longer
life than Comparison catalyst 4.

[0066] It is understood that the foregoing detailed description is given merely by way of
illustration and that many variations may be made therein without departing from the
spirit of this invention.
1. A catalyst support having a bidisperse micropore size distribution where the micropores
have an average pore diameter of less than 600 Angstrom units and being adapted for
use as a hydrotreating catalyst support for treating heavy feeds containing large
metal bearing molecules comprising a refractory oxide formate having
a) a small micropore region having an average pore diameter of less than 100 Angstrom
units; and
b) a large micropore region having an average pore diameter which is equal to or larger
than 100 Angstrom units and which is much larger than the average diameter of the
metal bearing molecules in a heavy feed to be processed;
the pore volume of the large micropore region comprising 10 to 90% of the total pore
volume; and
the pore volume of the small micropore region comprising 10 to 90% of the total pore
volume.
2. A catalyst support according to Claim 1, wherein the large micropores have an average
pore diameter which is at least five times the average diameter of the metal bearing
molecules in a heavy feed to be processed.
3. A catalyst support according to Claim 1, wherein the large micropores have an average
pore diameter between 100 and 600 Angstrom units.
4. A catalyst support according to Claim 3, wherein the large micropores have an average
diameter between 100 and 250 Angstrom units.
5. A catalyst support according to Claim 1, wherein the small and large micropore
regions are made of two different materials.
6. A catalyst support according to Claim 5, wherein the small micropore region is
made of alumina and the large micropore region is made of silica.
7. A method of making a catalyst support adapted for use as a hydrotreating catalyst
for treating heavy feeds containing large metal bearing molecules and having a bidisperse
micropore size distribution where the micropores have an average pore diameter of
less than 600 Angstrom units comprising
a) forming particles of a refractory oxide powder having
i) a small micropore region having an average pore diameter of less than 100 Angstrom
units; and
ii) a large micropore region having an average pore diameter which is much larger
than the average diameter of the metal bearing molecules in a heavy feed to be processed;
the pore volume of the large micropore region comprising 10 to 90% of the total pore
volume; and
the pore volume of the small micropore region comprising 10 to 90% of the total pore
volume; and
b) calcining the particles to form a catalyst support.
8. A method according to Claim 7, wherein the powder comprises a mixture of two powders
where one provides the small micropore region and the other provides the large micropore
region.
9. A method according to Claim 8, wherein the two powders are made of different materials.
10. A method according to Claim 9, wherein one powder is made of alumina to provide
the small micropore region and the other powder is made of silica to provide the large
micropore region.
11. A hydrotreating catalyst having a bidisperse micropore size distribution comprising
a catalyst support according to Claim 1, and
one or more catalytic metal components deposited on the support being selected from
the group consisting of the metals belonging to groups VB, VIB, VIIB and VIII of the
Periodic Table, said catalytic metal components being present in an amount of between
about 0.1% and about 30% in terms of metal oxide based on the total weight of said
catalyst.
12. A hydrotreating catalyst having a bidisperse micropore size distribution comprising
a refractory oxide formate having
a) a small micropore region having an average pore diameter of less than 100 Angstrom
units and having deposited thereon a catalytically effective amount of a desulfurization
metal oxide; and
b) a large micropore region having an average pore diameter in the range of 100 to
600 Angstrom units and having deposited thereon a catalytically effective amount of
a demetallation metal oxide;
the pore volume of the large micropore region comprising 10 to 90% of the total pore
volume; and
the pore volume of the small micropore region comprising 10 to 90% of the total pore
volume.
13. A hydrotreating catalyst according to Claim 12, wherein the metal in the desulfurization
metal oxide is selected from the group consisting
a) Group VIB metals which are Cr, Mo and W;
b) Group VIII metals which are Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt; and
c) mixtures thereof.
14. A hydrotreating catalyst according to Claim 13, wherein the desulfurization metals
are Mo and Co and wherein the Mo is present at a loading of from 8-30 wt% expressed
as MoO3 and wherein the Co is present at a loading of from 0.1-5 wt% expressed as CoO.
15. A hydrotreating catalyst according to Claim 12, wherein the metal in the demetallization
metal oxide is selected from the group consisting of
a) Group VIB metals which are Cr, Mo and W;
b) Group VIII metals which are Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt; and
c) Group VB metals which are V, Nb and Ta;
d) Group VIIB metals which are Mn, Tc and Re; and
e) mixtures thereof.
16. A hydrotreating catalyst according to Claim 15, wherein the demetallization metals
are Co and Mo and wherein the Mo is present at a loading of from 0.1-8 wt% expressed
as MoO3 and wherein the Co is present at a loading of from 0.1-2 wt% expressed as CoO.
17. A method of making a hydrotreating catalyst adapted for treating heavy feeds containing
large metal bearing molecules and having a bidisperse micropore size distribution
where the micropores have an average pore diameter of less than 600 Angstrom units
comprising
a) forming particles of a refractory oxide powder having
i) a small micropore region having an average pore diameter of less than 100 Angstrom
units; and
ii) a large micropore region having an average pore diameter which is much larger
than the average diameter of the metal bearing molecules in a heavy feed to be processed;
the pore volume of the large micropore region comprising 10 to 90% of the total pore
volume; and
the pore volume of the small micropore region comprising 10 to 90% of the total pore
volume;
b) calcining the particles to form a catalyst support; and
c) impregnating the calcined support with one or more catalytic metal components selected
from the group consisting of a metal belonging to Group VB, VIB, VIIB and VIII of
the Periodic Table, said catalytic metal components being present in an amount of
between about O.I* and about 30% in terms of metal oxide based on the total weight
of said catalyst.
18. A method of making a hydrotreating catalyst adapted for treating heavy feeds containing
large metal bearing molecules and having a bidisperse micropore size distribution
where the micropores have an average pore diameter of less than 600 Angstrom units
comprising
a) impregnating particles of a refractory oxide powder having a small micropore region
with an average pore diameter of less than 100 Angstrom units with one or more catalytic
metal components selected from the group consisting of the metals belonging to Group
VIB and VIII of the Periodic Table;
b) mixing the impregnated particles from step (a) with a refractory oxide powder having
a large micropore region with an average pore diameter which is much larger than the
average diameter of the metal bearing molecules in a heavy feed to be processed;
c) forming catalyst particles from the mixture; and
d) calcining the particles to form a hydrotreating catalyst.
19. A method according to Claim 18, wherein after step (c) the catalyst particles
are further impregnated with one or more demetallization catalytic metal components
selected from the group consisting of a metal belonging to Group VB, VIB, VIIB and
VIII of the Periodic Table.
20. A method of making a hydrotreating catalyst adapted for treating heavy feeds containing
large metal bearing molecules and having a bidisperse micropore size distribution
where the micropores have an average pore diameter of less than 600 Angstrom units
comprising
a) mixing and mulling together
i) a refractory oxide powder having a small micropore region wih an average pore diameter
of less than 100 Angstrom units which has impregnated thereon one or more catalytic
metal components selected from the group consisting of metals belonging to Group VIB
and VIII of the Periodic Table, and
ii) a refractory oxide powder having a large micropore region with an average pore
diameter which is much larger than the average diameter of the metal bearing molecules
in a heavy feed to be processed with one or more demetallization catalytic metal components
selected from the group consisting of a metal belonging to Group VB, VIB, VIIB and
VIII of the Periodic Table;
b) forming the mixture from step (a) into particles; and
c) calcining the particles to form a hydrotreating catalyst.
21. A method according to Claim 20, wherein before mixing
a) the refractory oxide powder having a small micropore region is impregnated with
one or more catalytic metal components selected from the group consisting of the metals
belonging to Group VIB and VIII of the Periodic Table; and
b) the refractory oxide powder having a large micropore region is impregnated with
one or more demetallization catalytic metal components selected from the group consisting
of a metal belonging to Group VB, VIB, VIIB and VIII of the Periodic Table.
22. A process for hydrotreating a heavy hydrocarbon oil containing asphaltenes, said
process comprising the step of:
reacting the heavy hydrocarbon oil with hydrogen at a temperature of between 300°
and 500°C, a hydrogen pressure of between 50 and 250 atm. and a liquid space velocity
of between 0.1 and 10 hour in the presence of a catalyst comprising:
a porous carrier composed of one or more inorganic oxides of at least one member selected
from the group consisting of the elements belonging to Groups IIA, IIIA, IVA and VA
of the Periodic Table; and
one or more catalytic metal components composited with said carrier, the metal of
said catalytic metal components being selected from the group consisting of the metals
belonging to Groups VB, VIB, VIIB and VIII of the Periodic Table, said catalytic metal
components being present in an amount of between about 0.1% and about 30% in terms
of metal oxide based on the total weight of said catalyst, said catalyst having a
bidisperse micropore size distribution comprising a refractory oxide particle having
a) large micropores having pore diameters in the range of 100 to 600 Angstrom units;
and
b) small micropores having pore diameters of less than 100 Angstrom units;
the pore volume of the large micropores comprising 10 to 90% of the total pore volume;
and
the pore volume of the small micropores comprising 10 to 90% of the total pore volume.
23. A process according to Claim 22, wherein the metal in the desulfurization metal
oxide is selected from the group consisting
a) Group VIB metals which are Cr, Mo and W;
b) Group VIII metals which are Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt; and
c) mixtures thereof.
24. A process according to Claim 23, wherein the desulfurization metals are Mo and
Co and wherein the Mo is present at a loading of from 8-30 wt% expressed as MoO3 and wherein the Co is present at a loading of from 0.1-5 wt% expressed as CoO.
25. A process according to Claim 22, wherein the metal in the demetallization metal
oxide is selected from the group consisting of
a) Group VIB metals which are Cr, Mo and W;
b) Group VIII metals which are Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt; and
c) Group VB metals which are V, Nb and Ta;
d) Group VIIB metals which are Mn, Tc and Re; and
e) mixtures thereof.
26. A process according to Claim 25, wherein the demetallization metals are Co and
Mo and wherein the Mo is present at a loading of from 0.1-8 wt% expressed as Mo03
and wherein the Co is present at a loading of from 0.1-2 wt% expressed as CoO.